AS7225
Director Demo Kit User Guide
The board also has the test points for 12V, 3.3V, 5V, and GND. It would be convenient for
engineering development.
3.3 AS7225
The AS7225 serves as a White Color Director for a companion host MCU. When a white color
target is set, AS7225 measures the current CCT and provides high level calculated white color
tuning control loop information for onboard LED channel PWMs to the host MCU via I
2
C registers.
The host MCU configures the PWM outputs to drive external MOSFETs for the target CCT. The
CCT gradually matches to the target CCT.
Silimarly with ams TSL4531 is attached, the director operation also provides illuminance control
information for Daylighting. TSL4531 reports the lux value and AS7225 provides the control
information. Without ams TSL4531 attached, AS7225 will report the lux value for inside area of
diffuser.
On the current external sensor board, U2 is TSL4531 and U3 is the temperature and humity sensor
on another side. When test with TSL4531, TSL4531 should be pointed to the tested area.
If AS7225 demo board is used to test with a real luminaire, please point AS7225 inward for white
color tuning applications and point out of the luminaire for daylighting.
3.4 Microcontroller
3.4.1 Interface
The onboard MCU provides UART interface to communicate to AS7225 Evaluation User Interface
software or other terminal software. The cable with USB and MicroUSB connectors is not a regular
USB download cable for a cell phone. The cable converts the signals between USB and UART so
please use the cable provided by the demo kit.
The MCU also receives the control loop information from AS7225 via I
2
C interface and drives
MOSFETs with PWMs for onboard LEDs control. The MCU is the master of I
2
C and AS7225 is the
slave. Please note AS7225 can be also the master of I
2
C when it controls TSL4531 sensor.
3.4.2 Firmware Update
Please visit download.ams.com for avaiable firmware and utility.
The MCU firmware can be updated with AS7225 Evaluation User Interface software version 0.7.x or
later. Please refer to the user guide for detail information.
The firmware can be also updated with the command line utility. Please copy the utility software,
efm8load.exe, and a firmware, AS7225host_xx_xx_xx.efm, into same folder and check the comm
port number for AS7225 demo kit. Then follow the steps below to update the firmware.
1. Run a terminal application with the comm port configured as 115200 Baud Rate, 8-Bit Data,
No Plarity, 1-Bit Stop.
2. Type “BL = 1” in the terminal window. This command sets the MCU into bootload mode.
3. Close the terminal application.
4. Run a command line window (Start -> Run -> cmd) and navigate to the folder of the utility
and the firmware.
5. Type “efm8load –p com3 AS7225host_xx_xx_xx.efm8” and press the return key. The com3
should be replaced with your comm port number.